Quick review of JDM underbody panels
 

A while back (right after I bought my BRZ) I bought the JDM underbody panels for my car. Though it was a while back I wasn't able to find all that much info on them so I figure I might as well write up a quick review and post some pictures (something that I also found hard to find when I looked).
For reference I bought them from mann engineering for something like $400 (they are in my area so I could just drive over and pick them up).

Reason I got the panels: I know they are supposed to decrease the coefficient of drag by a small amount. I didn't buy them for that (if it made a huge difference I think they would have been stock). Instead I got them hoping for some reduction in the cabin noise on the Freeway. They did in fact reduce the noise in the cabin so I don't regret the purchase decision. That said a few sheets of dynamat spread around the inside of the cabin (especially in the rear wheel arches) made a much larger difference for substantially less work.

About the installation: I didn't have a good way to get the car up on jacks to get under it so I had my local mechanic put the panels on during my first oil change. Took them a couple of minutes and there was no fuss. Everything was a direct bolt on after removing the smaller panels that come on a USDM car.

Pictures should be attached, first two are before, second two are after. I have an album of them at: https://plus.google.com/photos/10923...CJ7j3M2dubTsaw

Question for you. Did your underpanels come with hardware for mounting or did you purchase that separately?

Have you noticed any difference while on the highway? Assuming there's less turbulence under there with the panels I guess the car may be slightly less prone to wander due to wind?

I'd think you would feel slightly more stability/traction on high speed crests.

All the mounting hardware came with it. It was super trivial for them to install.

The only major difference I noticed was in the noise level on the highway. That said my A/B comparison was on a fairly level, smooth section of the highway so the car was generally settled and I didn't do anything crazy to upset the car. Frankly I never got any sense of instability at highway speeds before or after with this car.

Is it the same hardware mentioned in this link?

http://www.ft86club.com/forums/showp...82&postcount=1

I ordered the panels and there was a gaping hole in the middle of the blue bubble wrap with no hardware. The vendor told me it comes with no hardware, I have to buy each clip, screw and nut individually. I'm trying to get to the bottom of the truth.

You don't happen to still have the part number that would have been on the bag of hardware do you?

Do the JDM panels weigh significantly more?

It was a while back so I don't remember the details exactly but it did seem similar to the ones in the picture. I think all the panels came in clear plastic bags with some Subaru logos and part number stickers. The kit I got I believe (caveat that it was a while ago) even had Subaru part numbers for the bolts.
Overall I think you best bet might be to call up one of the other suppliers; mann engineering has their kit here: http://www.mann-engineering.com/prod...s-2013-brzfr-s and they say it comes with all the parts to attach the panels (mine did). Since it was a while back I don't remember where else I saw having the panels for sale but I remember that there were a few others.

Sorry I don't remember more details :(

I wouldn't say significantly more. They do weight more but then again the USDM version is really tiny so that isn't hard to do. Picking them up they felt lighter than I expected them to but they probably weighed a few pounds.

Great post, I'm after a quieter interior as well. I wonder if there's much space between the panel and the steel body. I would try to stuff some weather resistant in between. Maybe not stuff a lot because then it could collect moisture etc.

The thousands of rocks in my JDM aero panels would agree there is plenty of room between the panels and the steel body.

Ah thanks. Actually I meant from the stock Panels... or are they the same size just different thickness?

The JDM panels should have more room in between the panels and the steel as they are hollow and have much deeper channels than stock.